Control device



W. E. LEVINE CONTROL DEVICE June 4, 1968 5 Sheets-Sheet 1 Filed Feb. 5,1965 FIG. 1

INVENTOR. WALTER E. LEVI NE BY 9 g 59 g ATTORNEYS June 4, 1968 w. E.LEVINE 3,386,411

CONTROL DEVICE Filed Feb. 5, 1965 5 Sheets-Sheet 75 INVENTOR. WALTER E.LEVI NE ATTORNEYS Filed Feb. 5, 1965 June 4, 1968 w. E. LEVINE 3,386,411

CONTROL DEVICE 5 Sheets-Sheet 5 INVENTOR. WALTER E. LEVINE ATTORNEYSUnited. States Patent Oflice 3,386,411 CONTROL DEVICE Walter Eli Levine,Hamden, Conn., assignor to Dresser Industries, Inc., Stratlord, Come, acorporation of Delaware Filed Feb. 5, 1965, Ser. No. 430,712 4 Claims.(Cl. 116-129) ABSTRACT OF THE DISCLOSURE A pressure actuated switch foruse in an explosion susceptible atmosphere having an external knob whichis operable to internally set the switch point conditions and includinglocking means to prevent subsequent unauthorized resetting of the presetswitch conditions.

This invention relates to improvements in the construction of devices ofthe type actuated by changes in fluid pressure and operative in anexplosion susceptible atmosphere for, in turn, controlling associateddevices.

The objects include that of providing in such a device an explosionproof housing, to establish a fluid pressure seal between the housingand a transparent crystal forming a part thereof, to lock the operatingmechanism in the housing to prevent undesired displacement and toprovide a locking mechanism for a control element which is used to setthe upper and lower limits of the operating range of the device.

The exact nature of the constructions employed to accomplish theseobjectives are illustrated in full detail in a preferred embodimentappearing in the accompanying drawings.

In those drawings:

FIGURE 1 is a front elevational view of a control device in accordancewith this invention, with some parts broken away for better illustrativepurposes;

FIGURE 2 is a side elevational view of the structure of FIGURE 1, withmuch of the housing broken away to show parts in cross section;

FIGURE 3 is a front elevational view, partly in section, of a detail ofconstruction as it would appear from line 33 of FIGURE 2; and

FIGURE 4 is a similar view as it would appear from line 44 of FIGURE 2.

The particular form of the invention comprises a device which isoperated by changes in pressure of a fluid such as a gas, by convertingthe movements of a pressure distortable spring, such as a Bourdonspring, into forces for actuating, in this case, an electric switch ofthe mercury type, as will appear hereinafter to those skilled in theart. The subject matter comprising the invention herein disclosed is notlimited in its use to this particular form of device.

As illustrated, the device includes a heavy, preferably metal, casingconsisting of a rear wall 12, see FIG. 2, having radially projectingears 12a for attachment to any supporting member and an integral annularwall 14 forming a compartment for the actuating mechanism. The open sideof the annular wall 14 is counterbored and internally threaded at 18 toreceive a heavy ring 16, likewise, preferably of metal, which isexternally threaded for engagement with the threads 18. As illustrated,in FIG. 2, the ring 16, when rotated to final position, may be locked inthat position by means of a threaded Allen screw 20, which engages in arecess 22 in the wall 14.

As can be seen from FIGS. 1 and 2 the heavy ring 16 is provided with anintegral radially extending arm 24, in which is supported in an aperturea sleeve 26. The sleeve is provided with a head 28 and its opposite endis threaded to receive a clamping nut 30.

3,386,411 Patented June 4, 1968 A transparent disk or crystal 32 ofsuitable glass, for example, is firmly held on an annular seat formed onthe inner face of the ring 16 by means of the sleeve 26, which passesthrough a central aperture in the crystal and through a hole in the arm24. When the nut 30 is applied under pressure it will clamp the crystalagainst the annular seat on the ring 16 and will slightly how itoutwardly to produce a very effective fluid pressure sea] at the annularseat. The arm 24 is relieved between the seat at its free end, as shownat R in FIGURE 2. The plane of the seat S at the end of the arm 24 isslightly to the left of the plane of the annular seat on the ring, seeFIG. 2, so that when the nut 30 is drawn up the glass 32 will be sprungoutwardly or made to take a slightly domed shape in the central region,thereby greatly increasing the pressure between it and its annular facewhich overlaps the annular seat on the ring.

The sleeve 26 has a central bore in which a rotatable shaft 36 ismounted. Secured to the inner end of the shaft is an arm 34 having anaxially extending terminal finger 34a, which lies close to the face ofthe dial 52. The other end of the shaft 36 is provided with a knurledfinger knob 38 and a compression spring 40 is interposed by the knob 38and the nut 30 so that the arm 34 is normally held spaced from the dial52. When the knob 38 is pushed upon the arm 34 is shifted, so that itsterminal extension 34a will be moved close to the face of the dial 52,so as to be engageable with the terminal ends 42 and 44 of a pair oflevers 43 and 45 pivotally mounted behind the dial on a bushing 47 asmore completely shown in Du Bois et al. Patent 3,225,622. The ends 42and 44 are provided with pointed indicia 42a and 44a cooperating withthe scale 52a on the dial. Thus, the two levers which terminate in thedisks 42 and 44 can each be indemndently shifted with respect to thedial graduations by rotating the knob 38 with the lever 34 pushedinwardly, so that its end 34a can independently engage those disks. Thelevers which terminate in those disks adjust the mechanism in thehousing for minimum and maximum control limits, that is, provide a rangeof control terminating at its limits so that the operating mechanism ofthe device can actuate in this case a mercury switch, not shown, to eachof two positions. This actuation occurs at each end of the range. Thisoperating mechanism forms no part of this invention, being the subjectmatter of a co-pending application which has matured into theaforementioned US. Patent 3,225,622. As soon as the pressure on the knob38 is released, the arm 34 will be moved back to the position shown inFIG. 2 by the spring 40, whereupon the arm 34 can be rotated to aninactive position. This position is indicated in FIG. 1 and will bereferred to later.

In order to make this device tamper-proof, that is, to preventunauthorized shifting of the levers connected to the disks 42 and 44, alocking arrangement is provided to hold the arm 34 in a retractedposition, preferably that shown in FIG. 1. As will be seen from FIGS. 1and 2., the arm 24 is provided with a pair of raised sides 24a forming achannel in which a locking bar 46 can be positioned. This locking bar,as illustrated, is in the form of a thin metal channel which can be slidin between the raised sides 24a so that its inner end passes in back ofthe knob 38. The end of the bar 46 is notched to fit around the nut 30,see FIG. 1, and when seated can be locked in that position by means of apin 48, which passes through the raised sides 24a of the arm 24. Thispin can be held in that position by means of a cotter pin 50 or, ifdesired, a key actuated lock can be used. With the locking barpositioned, as shown in FIGS. 1 and 2, the knob 38 cannot be pushedinwardly and if the bar fits tightly enough the knob cannot even beturned.

For descriptive purposes, reference is made to the Bourdon spring 54,the interior of which is in communication with a coupler. This couplercomprises a pipe 58 having a threaded free end for connection to thesource of pressure fluid and external threads 60 for mounting in theinternally threaded sleeve 62, and a terminal head 56. The tube 58 andthe head 56 have a passage therethrough and the Bourdon spring 54 isconnected to the head 56, see FIG. 4, so that pressure fluid can be fedinto the spring. This part of the structure is conventional. However,the sleeve 62 is externally threaded so that it can be screwed into athreaded opening 64 in the wall 14 of the housing, see FIG. 2.

Secured in any suitable manner, as by brazing or welding to one face ofthe head 56 at B is a plate 66. Mounted on the outer face of this plate,see FIG. 2, is another plate 68 and the two are secured together bymeans of the machine screws 70. Formed on the inner face of the rearwall 12 are the bosses 12b and the plate 68 is secured firmly againstthese bosses by means of the machine screws 72. It is noted that theplane of the faces of the bosses 12b is slightly to the right, FIG. 2,of the rear face of the plate 68 when the screws 72 are loose. However,when these screws are drawn up tight the p-lates are tilted a bit to theright, and being secured to the head 56 of the coupler 58 that couplerwill be tilted in the sleeve 62, and that sleeve will be tilted in thethreaded opening 64 sufficiently so that all these parts are in a sensejammed. This provides a self-locking feature, which also provides a goodcooling path for the heat from any gas which will be present, should anexplosive condition which ignites the gas Within the housing occur. Itmay be noted that when the screws 72 are loosened the sleeve 60 willbecome relatively free for withdrawal.

Mounted on the face of the dial 52, see FIGS. 2 and 3, is a circuitconnection block 76, which is held on the dial by means of tabs 72astruck out from the dial and bent over in apertures on the base of theblock assembly. The circuit wires from the mercury switch of the deviceleading to the block are shown at CW. Mounted on top of this block is ap-late 78 which has an upstanding tab 78a, see FIGS. 2 and 3, of suchwidth as to provide a stop for the inactive position of the arm 34. Itwill be seen that the inactive position for this arm could be eitherthat shown in FIG. 3 or around to the other side of the stop 78a.

The various parts of the operating mechanism as previously mentionedform no part of this invention and so are not further detailed herein.

From the above disclosure it will be apparent that the features ofnovelty herein disclosed are capable of some variation by those skilledin the art and it is desired, therefore, that the scope of protectionafforded hereby be determined by the appended claims.

What is claimed is:

1. In a condition control instrument including a casing enclosing agraduated dial, a pair of adjustably setta'ble levers overlying the rimof said dial, each of said levers defining a control point of theinstrument in relation to the dial graduation at its setting, a bezelring connected to said casing and securing a crystal overlying saiddial, lever setting means operable through an aperture in said crystalfor selectively setting said levers at conditions to be controlled, saidlever setting means including a lever setting arm positioned interior ofsaid crystal, hand operable means adjustable exterior of said crystal,connecting means connecting said hand operable means through saidcrystal to said lever setting arm, said lever setting arm and handoperable means being unitarily movable for effecting arcuate and axialmovement with respect to said crystal the latter being between a firstposition in which said lever setting arm is operative in the plane ofsaid levers and said hand operable means is relatively close spaced tosaid crystal to a second position in which said lever setting arm isremoved to become inoperative in the plane of said levers and said handoperable means is further removed from said crystal than when in saidfirst position, the improvement comprising lock means to secure saidlever setting means against resetting of said levers, said lock meanscomprising a brace secured to said bezel ring and formed including apair of elongated spaced arms seating against said crystal and raisedtherefrom located to include therebetween said connecting means to saidlever setting arm, and a removable bar supportable between said spacedarms to underlie said hand operable means when in said second positionto prevent axial movement thereof to its first position. i

2. The improvement according to claim 1 wherein said bar is bifurcatedand when in position underlying said hand operable means effects aninterlock against rotation thereof.

3. The improvement according to claim 1 wherein said bezel ring isconnectably secured to said casing and said bar when in position betweensaid spaced arms renders the secured connection between said bezel ringand easing substantially inaccessible.

4. The improvement according to claim 1 wherein said spaced arms includetransversely aligned apertures in the raised portions thereof receivinga member extending therethrough to prevent removal of said bar.

References Cited UNITED STATES PATENTS 1,018,582 2/1912 Nelson 116-1291,397,518 11/1921 Hem 116-129 1,686,635 10/1928 Mylius et a1 116-1291,881,389 10/1932 Ricketts 116-129 2,156,085 4/1939 Dardani 116-1282,707,931 5/1955 Boat et a1. 116-124 3,045,638 7/1962 Davio 116-1293,150,634 9/1964 Rosen 116-124 3,175,531 3/1965 Du Bois- 116-1293,177,722 4/1965 Huston 73-418 3,225,622 12/1965 Du Bois et al. 73-415LOUIS I. CAPOZI, Primary Examiner.

